1. Field of the Invention
The present invention relates to a composite substrate for light emitting devices and a manufacturing method therefor.
2. Description of the Related Art
Light emitting diodes (LEDs) having various gallium nitride (GaN) layers on GaN single crystal and LEDs having various GaN layers on sapphire (α-alumina single crystal) are known as LEDs including single crystal substrates. For example, those LEDs are in mass production that have a structure formed by stacking an n-type GaN layer, a multiple quantum well (MQW) layer in which a quantum well layer composed of an InGaN layer and a barrier layer composed of a GaN layer are alternately stacked, and a p-type GaN layer in this order on a sapphire substrate. Moreover, a multi-layer substrate suitable for such use is also proposed. For example, Patent Document 1 (JP2012-184144A) discloses a gallium nitride crystal multi-layer substrate including a sapphire base substrate and a gallium nitride crystal layer formed by crystal growth on the substrate.